I think it is now a social construct. You meet neighbours and their kids, give them some candy - it's not the worst thing in the world by any stretch. The sweets are only bad if you let them eat the whole bag.
I don't think anyone is truly scared, the little ones love their costumes and older ones like getting a fright. One of our neighbours had a large scarecrow in the garden for weeks in the run up to halloween and then on the night he took it's place. Every 10 minutes you'd hear a mass of screams and then laughter.
Only the puritanical types like the WTS find "evil" in everything. So what if it had pagan origins - so do many other things like getting married in white and wedding rings but they are OK with those.